Environment Report 2018

ENVIRONMENT REPORT 2018

Produced Water Composition Produced water accumulates small amounts of naturally occurring substances through contact with the reservoir rock, including dispersed oil, dissolved organic compounds, naturally occurring radioactive materials (NORM) and production chemicals injected into the process. The composition of produced water is determined by the reservoir geology, maturity and the stage of production life. Dispersed Oil in Produced Water Around 2,140 tonnes of dispersed oil were discharged to sea with produced water, making up just over 0.001 per cent of the total mass of producedwater. The total mass of dispersed oil discharged increased by 6 per cent from 2016. OSPAR Recommendation 2001/1 requires that individual installations do not exceed an average dispersed oil-in-water concentration of 30 milligrams per litre (mg/l). In 2017, the average concentration across industry was 15.3 mg/l, up from 13.3 mg/l in 2016. At such low concentrations, oil rapidly disperses and is quickly broken down by naturally occurring bacteria.

International Comparison

The concentration of oil in produced water on the UKCS remains comparable to global and Norwegian values. The global average was 15.2 mg/l in 2017 while Norwegian data show concentrations of 12.1 mg/l. 4

Figure 3: Dispersed Oil Discharged with Produced Water to Sea

Oil Discharged with Produced Water

Oil in Water Concentration Limit

Average Oil Concentration with IR Method

Average Oil Concentration with GC-FID Method

7,000

35

6,000

30

5,000

25

20

4,000

15

3,000

10

2,000

5

1,000

Oil in Water Concentration (mg/L)

Oil Discharged with Produced Water (Tonnes)

0

0

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

2012

2013

2014

2015

2016

2017

Source: EEMS October 2018

4 See Norsk Olje & Gass Environmental Report 2018 at https://www.norskoljeoggass.no/globalassets/dokumenter/miljo/miljorapporter/environmental-report-2018.pdf

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